1. Field of Invention
The present invention relates to a display apparatus. More particularly, the present invention relates to a liquid crystal display (LCD).
2. Description of Related Art
With respect to a LCD, a pixel aperture ratio directly affects the utilization rate of a backlight source, and also affects the display brightness of the LCD. One of the major factors affecting the pixel aperture ratio is the area of a contact hole disposed on a thin film transistor (TFT) array substrate. Generally speaking, if the area of the contact hole is smaller, the area of a pixel region will be larger, and also the pixel aspect ratio will be larger.
However, due to the limitation of the current etching technique, if the area of the contact hole is too small, the contact hole in general cannot pass through an insulation layer smoothly. Particularly, with respect to a COA (Color Filter On Array) structure or an UHA (Ultra High Aperture) structure, since it is very difficult for the current etching technique to fabricate a contact hole having a high aspect ratio on a color resist, the contact hole has to be designed to have a sufficiently large area so as to ensure a certain yield level. However, this design will definitely affect the pixel aperture ratio. Hence, a designer is usually trapped in this dilemma and cannot have a breakthrough.